Production of vacuums



Nov. 13, 1951 FEUER 2,574,820

PRODUCTION OF VACUUMS Filed Oct. 15, 1945 IN V EN TOR.

Q mm Ffl/ER.

ATTORNE L Patented Nov. 13, 1951 "UNITED STATES PATENT OFFICE This invention relates generally to the production of vacuum and more particularly to the production of ultra high vacuum.

This invention also deals with the production 'of ultra high vacuums in sealed-01f tubes, for example, X-ray, Cyclotron, Van de Graaf generator, Betatron electronic tubes, etc., where it is essential to produce and maintain a high vacuum.

It is an object of the present invention to produce vacuum by the application of radioactivity.

It is a further object of the present invention ,to produce vacuum by the utilization of a disintegrating or nuclearv transmuting gas or gases, a ifurther object being. a method of out-gassing "chambers and electronic tubes.

It is a still further object of the presentinvention to produce ultra high vacuum by employing fission as a source of energy.

It is yet another object of the present invention to produce vacuum without employing diffusion pumps.

.Another object of-the present invention is to I produce vacuum by displacement.

The theory embodied in the production of the said high vacuum resides in that when substances are bombarded by high speed particles (alpha, beta, proton, neutron, deuteron) artificial radioactive substances may be produced. Some of these substances may be gases, liquids, or solids of long or short lifetime with various emissions which determine the methods of separation for said use. At present only a few of the substances possess the desired properties and suitable characteristics, such as, beinga radioactive gas of moderate life time (that is, one which is not too short to work with) which upon disintegration or nuclear transmutation will produce a non-disintegrating solid or one whose disintegrations will not affect the property of the vacuum. Beta, positron, neutron radiation are negligible unless they in turn produce secondary by-products which are harmful. Thus, if a radioactive gas upon disintegration or nuclear transmutation leaves behind a solid material, the resulting vapor pressure will be the sum of that of the disintegrated solid plus that of the solids composing the chamber. The pressure may be measured electrically or may be calculated.

8' Claims. (Cl. 316 --24) The following equations illustrate types of reactions:

Radioactive nitrogen 1s C1a o 1 a +1 (Half life time=11 minutes) Radioactive chlorine C a4 ,,gs4+ o 11 16 +1 (Half life time=40 minutes) Radioactive argon A41 ,K41+o 1s 19 -1 g I (Half lifetime=110 minutes) These reactions do 'not exclude any other radioactive types. It is "desirable, however, that there be no alpha or protrons as by-products.

The method of production and. separation of said radioactive products is not within the scope of this invention, the latter being primarily con-" cerned with the application of artificial or natural radioactive products to the production of high vacuums; However, some of the methods used for their production will now be stated:

(A) Bombardment by naturally radioactive elements (alpha bombardment) followed by :v

1a ,c'1a 0 7 +1 (Half life time=11 minutes) (B) Bombardment by artificially produced deuterons. Production of high speed particles by physical means.

012 2 14 ,N1s 1 c 1 7 7 0 followed by:

ia ,C 1a 0 7 6 +1 (Half life time=11 minutes) (C) Bombardment by neutrons. Neutron sources may be radium-beryllium, etc., or fission produced sources.

The radioactive gas may be collected after separation and used for vacuum production without the interference of heavy corpuscular particles. Thus, the production of the radioactive gas may be either by natural or artificial means.

The vacuum achieved is dependent upon the materials which compose the vacuum chamber or tube (the metallic anode Cu, Au), glass walls of the chamber, the primary out-gassing of the chamber (electronic tubes, etc), the rate of exhausting the gas within the chamber; the half life time of the radioactive gas (which influences the working time), the leakage of the tube and the degree of concentration or dilution of the radioactive gas.

The method of evacuating the chamber may be l and E represent manometers, E to measure B pressure without A, C and D and vacuum pump that of already standardized methods; however, the principle of fractional reduction of the'gas must be carried out by concentration or dilution followed by evacuation of the gas before any apreached. ".Another'variation may be to place thegas which is to be bombarded in the intended vacuum chamber and'produ'ce the disintegrating or nuclear transmuting-gas which in time will result in the intended vacuum.

In producing said vacuum,,the following apparatus may be employed: a'normal evacuating system plus a chamber containing 'a'supply of radioactive gas. It may be mentioned here that a high degree of vacuum may be obtained without any high vacuum diilfusionpumpyfor by the frac-- tional removal of one gas (the non-radioactive one) replacing it by a radioactive disintegrating one the vacuum is produced after a period of waiting.

It may be further mentioned that after the chamber is sealed attempts can be made to con- "ce'ntrate the gas and 'thus deposit the disintegratedsolid in a limited region by means of an electric'current. 7

Example of process: Method A.'-A normal 1 liter flask containing air is evacuated to a pressure of 10- mm.; the flask is then filled with 1 liter radioactive nitrogen and evacuated immediately upon filling and then sealed. The ratio I of the volume of radioactive nitrogen to the amount of gas pressure finally evacuated will give the limit of the vacuum. Thus, if the pressure before sealing was 10- mm. the final'vacuum pressure would be 10- mm. If it were 10- mm. the final pressure would be 10- mm. upon the disintegration of the nitrogen. This is for a volume of 1 liter. The principle may be applied to produce vacuum as high as the combined vapor pressures of the ,materials within the tube (theoretically) and the maximum amount of external pressure it canwithstand, dependent upon th -,p ys a1 o i soithe tube. V V V Example of process M ethod B.The same procedure in reverse is applied; that is, thechamber is subjeeted'to pressure from a radioactive disintegrating or nuclear transmuting gas and then evacuating it achieving similar results.

Example of process: Meth d C'.-A gas which upon bombardment will disintegrate (with desired properties) is placed in a chamber such that -it occupies the entire volume (all'other gases having been previously removed so that this may be. considered as the sole gas). The tube is then bombarded and the gas in turn is radioactivated with its characteristic half life time; the tube or preciable decomposition occurs in order to obtain; 7 the highest degree of vacuum. This processmay be repeated until the desired degree of vacuum is chamber is allowed to remain until the'desired vacuum is reached.

The figure in the drawing will serve to illustrate a method of producing vacuum utilizing radioactive gas or gases. It is understood, however, that this method is exemplary only and is not intended to limit the scope of the invention to the example herein given. I

In the drawing which shows a system of producing vacuum by radioactive meansQthe letter A represents a chamber containing radioactive gas having suitable characteristics; B the cham- F in system, if desired. Pressure may also be measured'electrically, if desired. The numerals I, 2, 3, 4, 5, 6, 1 and 8 are stop cocks controlling various" parts of system. It is desirable to place a mercury trap in the system.

Evacuation may be produced through Aty icaloperation: The system is exhausted with stop cocks l and 5 closed, and 2, 3; 4, 6,1 and 8; open; c10sing-2,.3, 4, I and Band now opening l, the radioactive gas is permitted to enter chamber B. Stop cock 6 is now opened and pr'essure B can be measured with manometer E, it being understood that a mercury trap'is in the system. In convenient arrangements substances and apparatusmay be placed in chamber B...,Co'cks 1,

.6, 4, and-2 are now opened and chamber Bis again exhausted, this time, of the radioactive'gas in B plus'the fractional original gas therein- Cocks 2, 4, 6 and ,1 are now closed. This operation may be repeated as desired depending upon the degree fication one of the modes in which it'is. contemplated embodying the invention, it is desired that'the invention in no way be limited to the details of such disclosure, for in the further practical application of the invention, changes may bejmade as circumstances require or experience suggests Without departing from the spirit of the invention within the scope of the appended claims:

Havingthus described the invention what is claimed as new and what isdesired to be se- 60:

cured by Letters Patent, is

1. The method of producing a vacuum in a chamber having a gas, which comprises introducing into'said chamber a radioactive gas which upon disintegration' forms a solid only, thereby increasing thepr'essure in said chamber'and simultaneously diluting the gaseous constituents in said chamber; evacuating said mixtureuntiha desired pressure is obtained; refilling said chain'- ber .with a radioactive gas which upondisintegration forms a solid only, thereby diluting the residual gas 'in' said chamber; again refilling said chamber'with a radioactive gas which upon disintegration forms a solid only, until the predetermined degreeqof vacuum is' reached, pifthen sealing said chamber and allowing the radio-- active gas to disintegrate into solid carbon for obtaining the final degree of vacuum desired.

2. The method of producing a vacuum in a chamber having a gas, according to claim 1, wherein said radioactive gas which upon disintegration forms a solid only, comprises radioactive nitrogen.

3. The method of producing a vacuum in a chamber, according to claim 1, wherein said radioactive gas which upon distintegration forms a solid only, comprises radioactive argon.

4. The method of producing a vacuum in a chamber, according to claim 1, wherein said radioactive gas which upon distintegration forms a solid only, comprises radioactive chlorine.

5. The method of producing a vacuum in a chamber which comprises fractionally displacing a gas of a non-disintegrating product with a disintegrating gas which upon disintegration forms a solid only, through a series of evacuations of first the non-disintegrating gas and then adding the disintegrating gas forming a mixture of the two gases, then alternately evacuating the subsequent mixture and upon the evacuation of each mixture diluting this mixture with a disintegrating gas of solid yielding product until the precalculated dilution has been reached, sealing the vessel after attaining a precalculated dilution, and leaving the residual disintegrating gas of solid yielding product to disintegrate until the final precalculated desired vacuum is reached.

6. The method of producing a vacuum in a chamber, according to claim 5, wherein said disintegrating gas is radioactive nitrogen.

'7. The method of producing a vacuum in a 6 chamber, according to claim 5, wherein said disintegrating gas is radioactive argon.

8. The method of producing a vacuum in a chamber, according to claim 5, wherein said disintegrating gas is radioactive chlorine.

IRVING FEUER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS page 182, Charles Scribners Sons, New York (1906).

Kaye: High Vacua, pp. 39-43, 119, 130, Longnans, Green and Co Ltd., London (1927) Chemical Abstracts, vol. 29, pp. 7, 127 (1935). Science, pp. 533-543, June 5, 1936. Pollard and Davidson, Applied Nuclear Physics, pp. 91, 107-115, John Wiley 8: Sons, Inc., N. Y. (1942). c 

